Rodent Bot Fly

HUGE FLY Please help me Bugman. . I caught this fly, however, this is the biggest fly I have ever seen!! Its over an inch long and its so fat it cant fly, maybe ready to give birth to a small child or something? I thought it was a bee of some kind at first but it resembles more of a fly than anything. The pictures make it look small but this thing has some serious girth to it. Let me know what I have please. I’m really boggled and amused!! Thanks, R.E

Hi R.E., This is some species of Bot Fly in the family Oestridae. They are also called Warble Flies. They are host specific. Some are parasitic on rodents like squirrels and rabbits, and there is a human Bot Fly in the tropics. The maggots burrow into the skin and cause a large bump with an open sore known as a warble. Not a pretty picture. Sorry we can’t identify the species. Perhaps Eric Eaton can. Here is what Eric wrote: “The bot fly is a rodent or rabbit bot in the genus Cuterebra. The adults do not feed. In fact, tey have no mouthparts! They live briefly, fueled by fat stored in the larval stage. Male bots practice ‘hilltopping,’ whereby they stake out a perch on a promontory, the better to intercept females flying below. These are not commonly-encountered flies, despite their relative abundance.”.